In general, the washing machine, a home appliance used the most generally, removes dirt from laundry, such as clothes and beddings by using a softening action of detergent, friction of a water circulation caused by rotation, and impact of the water to the laundry.
In the washing machines, there are pulsator type washing machines each having an upright drum, and drum type washing machines each having a drum laid down in a horizontal direction.
A washing cycle is a process for removing dirt from the laundry put into the drum together with detergent, and washing water by chemical action of detergent in washing water, and physical action of the drum.
A rinsing cycle is a process for rinsing the detergent and dirt from laundry by supplying washing water containing no detergent, and a spinning cycle is a process for rotating a washing tub at the high speed after finish of the rinsing cycle for extracting water from the laundry.
Because a related art washing machine consumes a large amount of washing water, recently there are efforts for minimizing an amount of the washing water used in the washing.
What has been developed as a result of such an effort is a washing machine with a steam generator, wherein the steam generator assists to progress a highly effective washing with a comparatively small amount of washing water by supplying high temperature steam to the drum.
In general, a function is provided to the user, in which a time required for a cycle is displayed on display means of the washing machine for the user to notice an entire cycle time or a remained cycle time during the washing is in progress.
The cycle time required for a cycle includes not only a time required for washing, rinsing, and spinning, but also a time required for water supply/drainage, and a time of the steam spray. While the time periods of the washing, the rinsing, the spinning are fixed depending on a washing course, the cycle time required for the steam spray varies with environments of application.
In a steam spray cycle, high temperature steam is sprayed to an inside of the drum, for heating washing water in the drum to a temperature higher than a preset temperature. However, in the steam spray cycle, an actual time required for heating the washing water to the preset temperature varies depending on the environment of application of the steam, i.e., a water pressure, use of hot/cold water, and so on.
Due to those reasons, a steam spray cycle time has been set and displayed, preliminarily.
Accordingly, once the steam spray cycle is started, the preliminarily set time is displayed, and the preliminarily set steam spray time is down counted according to a rate of temperature change of washing water heated by the steam sprayed thereto.
However, since an actual required time of the steam spray cycle varies with the environment of application, the preliminarily set time displayed on the display means can not, but shows an error with respect to an actual time taken.
For an example, because the rate of the washing water temperature change is high if a laundry amount is small, an interval of decrement of the down count of the preliminarily set time becomes greater, leading the displayed time to be changed rapidly. Opposite to this, because the rate of the washing water temperature change is low if a laundry amount is great, an interval of decrement of the down count of the preliminarily set time becomes smaller, leading the displayed time to be changed slowly, and if the decrement is small extremely, it can be misunderstood that the display time is standstill, temporarily.
That is, due to the error between the preliminarily set time set arbitrarily and the actual cycle time taken to reach to a preset temperature, the user is liable to misunderstood the rapid change or the temporary standstill of the display time as a fault of the washing machine. Moreover, the difficulty of estimating the required time of the steam spray impairs reliability of the washing machine.